While working with @fedify/fedify today, I came across a bug where the .well-known/webfinger route was returning 404.

After some debugging and chatting with the @fedify/fedify team, I realised that this problem only happened when used with Node.js.

Finally, after hours of debugging, I was able to identify the root cause as the behaviour of the url.domainToASCII.

import { domainToASCII } from 'node:url  
console.log(domainToASCII("localhost:8000"));  
console.log(domainToASCII("example.com:8000"));  

In deno, the hostname with port number (e.g.: example.com:8000) is considered valid input and returns the string as example.com:8000.

But in Node.js & Bun, domainToASCII will consider example.com:8000 as invalid input and return the empty string.

Below is the tabular form of return value of domainToASCII("example.com:8000") in various runtimes.

Hope this is Helpful.

Versions of Language/packages used in this post.